The purpose of this research is to develop the basic knowledge that is necessary for the understanding of bone remodeling in the femur of mature large mammals. A number of canine femora will be subjected to hypo- and hyperphysiological force levels in the diaphysis by means of an implant device. The changes in the bone tissue microstructure, the bone tissue histology, the stiffness of the femoral diaphysis, and the elastic properties of the bone tissue due to the altered force level will be quantified. The changes in bone shape and bone microstructure will be assessed from histological sections and enlargements of microradiographs of thin sections. The changes in the stiffness of the femoral diaphysis will be evaluated using a mechanical testing system. The changes in the elastic constants will be determined ultrasonically. This information will be summarized by the calculation of remodeling rate coefficients for internal, periosteal and endosteal remodeling. The remodeling rate coefficients represent the rate of deposition or reabsorption of bone tissue per unit time at a fixed stress level. This information can be used to predict the changing characteristics of mature bone tissue due to implanted prostheses and changes in activity level, such as bed rest or an intensive physical training program.